Week 3: Gesture has more than a position

Why a timing signal you compute yourself outlasts a hardware signal you merely read

8 March 2027

PointerEvent.pressure looks like the obvious way to make a mark expressive — it’s a number, right there on the event. It’s also unreliable: a mouse reports a constant 0.5, most touchscreens report 0 without a stylus that supports force, and a keyboard has no pressure at all. Reach for it and you’ve deepened one input path and quietly broken the course’s own standing rule that every instrument answers to more than one hand.

The signal that survives across mouse, touch and keyboard alike is timing: how long since the last event, how far the position moved in that interval. Compute it yourself from the event stream you already have, and every input device feeds it identically. The same reasoning goes one step further later in the semester — some expressive qualities aren’t tied to a single event at all, but to shared state a map or a counter already tracks, which is free across every input path for the same reason.

Outline#

• why pressure is the wrong first reach, device by device
• computing velocity and dwell time from your own event stream instead
• state-based signals as a further step past timing signals, for later weeks